Intracellular second messenger cAMP is involved in relaxation of airway smooth muscles and regulation of the functions of inflammatory cells. cAMP is broken down by phosphodiesterase (PDE) and becomes inactive 5'-AMP. It is considered that an increase in intracellular concentration of cAMP due to suppression of cAMP metabolism by PDE would give bronchodilating and anti-inflammatory actions and would exhibit a therapeutic effect on inflammatory diseases such as asthma [Eur. Respir. J., 7, 579 (1994)]. Up to now, PDE has been classified into five isozymes (i.e., types I to V PDE). Their distributions differ among on the tissue [Trends Pharm., Sci., 12, 19 (1991)]. This suggests a possibility that selective inhibitors of PDE isozymes would result in tissue specific increase of intracellular cAMP concentration.
It is reported that a selective inhibitor of type IV PDE isozyme suppresses inflammatory cells functions [Thorax, 46, 512 (1991)] and is useful for inflammatory diseases such as asthma [J. Pharmacol. Exp. Ther., 266, 306 (1993)] and dermatitis [Br. J. Pharmacol., 112, 332 (1994)] and autoimmune diseases such as multiple sclerosis [Nature Medicine, 1, 244 (1994)] and rheumatoid arthritis [Clin. Exp. Immunol., 100, 126 (1995)]. In addition, it is thought that cardiovascular side effect caused by non-selective PDE inhibitors such as theophylline could be reduced by using selective type IV PDE inhibitor. Rolipram having the following formula (Japanese Unexamined Patent Publication (Kokai) JP-A-50-157360) is known as a compound having a specific inhibitory activity against type IV PDE. ##STR2##
Other compounds having a specific inhibitory activity against type IV PDE are known (JP-A-62-281864, U.S. Pat. No. 5128358, WO 94/10118, WO 94/12461, JP-A-5-117239, JP-A-7-101861, WO 95/03794, WO 95/08534, etc.), but they have not been clinically applied up to now. Development of more useful compounds is desired. Further, JP-A-5-213893,discloses, as an antifungal agent, a compound having the following formula (II): ##STR3##
wherein, Ar represents an unsubstituted or substituted aryl group or heterocycle and n is 1 or 2. JP-A-6-1777 discloses, as an antifungal agent, a compound the following formula (III): ##STR4##
wherein, Ar represents an unsubstituted or substituted aryl group or a heterocyclic ring, n is 1 or 2, and Z is N or CH. JP-A-5-148248 discloses a compound having the following formula (IV): ##STR5##
wherein, R.sub.1 and R.sub.2 may be the same or different and represents a hydrogen atom or an unsubstituted or substituted phenyl group, R.sub.4 is an unsubstituted or substituted C.sub.1 to C.sub.10 alkyl group, R.sub.5 represents a C.sub.1 to C.sub.10 alkyl group, and n is 0 or 1, as a compound useful for the production of a carbapenem based antibiotic or carbacephem based antibiotic. JP-A-7-17946 discloses a compound having formula (V): ##STR6##
wherein, R.sub.1 to R.sub.6 each independently represent hydrogen; a C.sub.1 to C.sub.4 alkyl group; a hydroxy group; a C.sub.1 to C.sub.4 alkoxy group or a C.sub.1 to C.sub.4 alkyl group substituted with a --SO.sub.3 H group; a phenyl group; a benzyl group; a halogen atom; a phenyl group substituted with a C.sub.1 to C.sub.4 alkoxy group or a --SO.sub.3 H group; a benzyl group; and n is 0 or 1, as a starting material, when producing 2-(2'-aminoalkylmercapto)ethanol useful as a synthesis intermediate for a dye.